Field of the Invention
The present invention relates to a measuring device, a measuring method, a system and a manufacturing method.
Description of the Related Art
As a device for measuring a shape of a measurement object, an optical type measuring device which uses a pattern projection method is known. In the pattern projection method, a predetermined pattern of light is projected onto a measurement object to perform imaging, a pattern is detected from image data, and distance information on each pixel position is calculated from principles of triangulation, and thereby a shape of the measurement object is obtained. As the pattern projection method, a spatial coding method for performing binary encoding of a space by projecting a pattern of light alternately having bright lines and dark lines is often used. In order to improve measurement accuracy using the spatial coding method, it is necessary to accurately determine a boundary between a bright portion and a dark portion from obtained image data.
As a method of accurately determining a boundary between a bright portion and a dark portion, there is a method of projecting a first pattern of light which alternately has bright portions and dark portions and a second pattern of light which has the bright portions and the dark portions of the first pattern of light in reverse and is complementary to the first pattern of light, and determining intersection points of these patterns of light as a boundary. Respective patterns of light are complementary to each other, and as long as the same plane is measured, a distance between the intersection points coincides with a width of the bright portions (or a width of the dark portions). However, in actual measurement, due to an effect of ambient light (room light such as a fluorescent lamp), the complementary relationship collapses, and intersection point positions deviate in some cases. It is hard to distinguish whether deviations of the intersection point positions are caused by ambient light or are caused by a shape of a measurement object. As a result, measurement accuracy is lowered. As a method of reducing the effect of ambient light, a method of synchronizing imaging timing with a period of an integer multiple of a commercial power frequency (50 Hz, 60 Hz) to reduce the effect of ambient light is known (Japanese Patent Laid-Open No. 2009-19884).